I had to dispense an oil/gas mix into a small long necked bottle and was frustrated with how the off-the-shelf funnels spat and gurgled. With this funnel design, you pour the liquid into half of it, and the other half is the vent. with the long neck going into the bottle, the liquid has almost no chance of bubbling into the vacant half, and if it did, there is plenty of space to catch the debris and allow it to drain. It works really well. I added another funnel that i have created for a special application. You can resize in your slicer for your specific needs.